Comparative VS softwood pellets, advice and feedback?

[Christophe]

Hi friends,

I just got a stove pellet boiler (hey ... well!). It's a Thermorossi H2O 34 found not too expensive used (after small study it seems to be beefy, 260 kg and there is a cleaning system of the automatic brazier I will show you that later, for those in a hurry you can see the instructions below).

It's actually more of a boiler than a stove because it does not have an air blower (the air is only heated by the losses). I think he will be able to heat the whole house with some logs in addition

It's only been a week that I have it so I learn to domesticate the beast, it's not the same as a log stove! This actually requires much more attention than a conventional wood stove ... Cleaning all 2 3 days of the brazier, checking the draw (alarm) ...

Since a week and ten bags of 15 kg burned, I am pleasantly surprised by the little ash produced! I did not measure but it must be a few liters ...

Well I go astray, the topic I want to discuss here is the choice of pellets: coniferous or hardwood?

In fact this stove can burn both (may be like all pellet stoves ??? I find little information about this) and I would like to compare the 2 pellets following the feedback of experiences. other members.

a) Calorie / price ratio
b) Quality of the heater
c) Consumption
d) Clogging

For the past week, I've only been using Fireland 80 / 20 DIN Plus hardwood / softwood pellets. The seller told me that this stove was set on the hardwood pellets precisely ... but I did not see anything in the record as setting about it so ????

Fireland_pellets_feuillus.jpg (491.66 Kio) Viewed 41731 times

The price is (small promo) 3.69 (instead of 3.89) at the corner brico. Let 5.5 cents per kWh ...

In comparison, the 100% resinous of the same brand are 4.89 € the bag ... it is already a hell of a difference in price for the same kWh!

You have to believe that people prefer softwood pellets ... when they have to burn faster. A fir log heats up fast and strong but will never stand overnight, like an equivalent log of hardwood of the same size ... no reason that it is not the same for pellets?!?

So on the price, is clear that the advantage is for the moment to hardwood pellets ... For the other criteria I have no experience, hence this subject!

Here is the instructions for the Thermorossi H2O 34 in English (not found in French):

ecotherm_h2o.pdf

(2.47 million) Downloaded times 1473

ps: more questions and improvements will come later on this stove ... you know me

[Ahmed]

You write:

A fir log heats up fast and strong but will never stand overnight, like an equivalent log of hardwood of the same size ... no reason that it is not the same for pellets?!?

No, it's absolutely not comparable! A log should be considered a bundle of tubes: hardwoods have small tubes and softwoods wholesale, resulting in a significant difference in density; therefore, the amount of material is greater in a leafy log than in a coniferous tree, hence a lower calorific value.
When sawdust and chips are subjected to high pressure during the production of densified logs or pellets, this difference is offset, since the larger pipes are more crushed than the smaller ones, which gives roughly the same final density (with the advantage of resin on hardwoods ...).
There would be two advantages to softwood: more lignin (it is the binder of wood and pellet) allowing a better mechanical resistance of the granule *; resin, which is a good fuel. Of course, the choice also depends on the respective price of the different commercial formulations.

* The supply of softwoods acts as an improvement of this criterion, but it is not necessary to have a pellet in pure resinous ...

[Christophe]

Pardon, I should have said the same "mass" mea culpa ... and therefore with the same mass and same% humidity log that your analysis would be?

I think the difference is also chemical: the hardwood resin is very energetic ... no? It is clear that the flames are more intense and large (for the same draw) with resinous ...

Do you eat me?

Otherwise ok for the pellets, so it is kif kif at the level of the burning time. First point analyzed so!

[Did67]

The softwood has a slightly higher PCI, because of the presence of resins.

One site says this:

"at 20% humidity, hardwood (oak, beech, ash, hornbeam, etc.) will have a PCI of 3,8 kWh / kg and softwood (fir, pine) will have a PCI of 4,1 kWh / kg "

This well documented study of the ADEME [www.boisvivant.com/ftp/energie/fichier/cofor_1184244350_59.doc] gives:

Medium hardwood: 5 070

Medium resinous: 5 330

The difference is therefore less than 10%. There, I think it is dry wood.

But that does not justify such a difference in price!

You make an excel to correct the PCI gap - what you buy is kWh!

[Ahmed]

From a theoretical point of view the energy density of a resinous log is significantly higher than that of a hardwood issue: 4040 against 3850 kwh / kg (on average *), but in use it does not behave thus, unless one compresses at the same density, which is the case of pellets ...
There is also the case of soft hardwoods, which I have not mentioned and which are comparable to coniferous (big pipes), but without resin ...

*Source ADEME.

[Did67]

it is therefore kif kif at the level of the burning time.

The burning time, you do not care. It is up to your boiler to manage the inputs (pellets, combustion air) according to the needs [exactly to the regulation of your boiler]!

You, there are two parameters that concern you:

- the PCI per kg of your pellets (since you buy in kg)

- the efficiency of your boiler and therefore the cleanliness of your exchangers / the quality of the combustion air control [if the exchangers are not clean - the particles of a pellet boiler are "dry" and "felt", therefore insulating - the yield decreases; if your boiler over-ventilates too much, it throws calories up the chimney - they always over-ventilate a little, for safety: limit the CO].

[Christophe]

Ah, we agree, so the resin contributes well to improve the combustion and PCI of softwoods

Here are the characteristics of 80% hardwood pellets that I have:

pellets_fireland.jpg (189.03 Kio) Viewed 41715 times

So we are 16.5 / 3.6 = 4.6 kWh / kg

I'll have to buy some bags this afternoon, I'll take a picture of the characteristics of a softwood ... but in my opinion it will be the same (or in a handkerchief as you say Did ...)

[Ahmed]

The big difference in terms of caloric value is that so-called "dry" logs are, in reality, wetter than pellets: in general, around 20% for logs and, here, 10% for your pellets (provided that 'there is no moisture uptake) ...

[Christophe]

The burning time, you do not care. It is up to your boiler to manage the inputs (pellets, combustion air) according to the needs [exactly to the regulation of your boiler]!

Bin yes and no because unlike a boiler 100% automatic, a stove (boiler) pellets, it must be recharged, so a pellet that burns less quickly is less recharge ... me gourè I?

I have 65 kg reserve, I have not measured exactly the consumption I will do it soon.

In theory, the minimum power is 6 kW, ie one consumption per hour of 6 / (4.6 * 0.85) = 1.5 kg / h or 36 kg per day (with 85% efficiency and 4.6 kWh / kg ...).

From what I understood about regulation:

a) There are 5 fixed power modes + an automatic mode.
b) In automatic mode, the pan fills the power on the water
c) In fixed mode, it does not regulate (except stop in case of overheating), the power is given by the flow of pellets and combustion air

So in less than 2 days the reserve of 65 kg is logically burned.

Which requires a regular intervention, that is why a pellets that would last a little longer can be interesting for stoves!

You, there are two parameters that concern you:

- the PCI per kg of your pellets (since you buy in kg)

- the efficiency of your boiler and therefore the cleanliness of your exchangers / the quality of the combustion air control [if the exchangers are not clean - the particles of a pellet boiler are "dry" and "felt", therefore insulating - the yield decreases; if your boiler over-ventilates too much, it throws calories up the chimney - they always over-ventilate a little, for safety: limit the CO].

Yes OK!

I would like to make a performance measurement ... is there a simple and accessible method?

I think I remember an equation in heating oil which gives a "raw" estimate of the yield just with the measurement of the temperature of the fumes, is this also valid in pellets according to you?

[Did67]

The big difference in terms of caloric value is that so-called "dry" logs are, in reality, wetter than pellets: in general, around 20% for logs and, here, 10% for your pellets (provided that 'there is no moisture uptake) ...

10% is a limit.

Commercially, many manufacturers "guarantee" humidity levels below (7%), which allows them to "guarantee" a higher PCI. I have often seen (and used) softwoods at 5,0 kWh / kg.